Research Of Betaine Anhydrous Replacement For Methionine In Broiler Diets

Previous studies showed that methionine(Met)replacement with betaine in diet had no negative effect on the grow performance and carcass characteristics of broilers,but little attention has been paid to the influence on the digestive enzyme activities,meat quality and amino acids profile.Therefore,the objective of this study was conducted to investigate the effects of DL-Met replacement with betaine anhydrous on the grow performance,digestive enzyme activities,nutrient utilization,muscle oxidative status,meat quality and amino acids profile of broilers.A total of 192 1-day-old Arbor Acres broiler chickens were randomly divided into 4 groups with 6 replicates of 8 chickens,receiving a control basal diet containing 0.14%and 0.08%Met(Total Met:0.5%and 0.42%)during 1-21 d and 22-42 d,respectively,or one of the test diets supplemented with betaine anhydrous to replace Met at 25%(B25%),50%(B50%)and 100%(B100%),respectively.The study included three parts:Trial 1 was conducted to study the effects of Met replacement with betaine anhydrous on the grow performance,organ development and immune function of broilers.The results showed as follows:compared with the control,betaine inclusion groups did not influence the grow performance,organ indexes,content of growth hormone and insulin-like growth factor I,activities of metabolic enzymes and immune indicators in serum(P>0.05).But the 42 d liver index in B50%group was increased and the 21 d immunoglobulin G content in B100%group was decreased(P<0.05),when compared with B25%group.Trial 2,the objective of this experiment was to study the effects of Met replacement with betaine anhydrous on the carcass characteristics,serum physiological and biochemical parameters,digestive enzyme activities and nutrient utilization in broilers.The results showed as follows:chickens had similar carcass characteristics and content of crude protein and ether extract in breast muscle and liver among groups.Compared with the control,B50%and B100%groups decreased the 21 d total protein and blood urea nitrogen content and increased the 42 d triglyceride content(P<0.05).B100%group also decreased the content of globulin at 21 d(P<0.05).Chymotrypsin activity in pancreas was increased in B100%group and apparent metabolism rate of crude protein was increased in B50%group(P<0.05)as compared with the control.Trial 3,the aim of this experiment was to determin the effects of Met replacement with betaine anhydrous on the muscle oxidative status,meat quality and amino acids profile of broilers.Compared with the control,glutathione peroxidase activity and pH value of 24 h in breast muscle were significantly decreased in B100%group(P<0.05).In addition,an increased muscle 45-min pressure loss(P<0.05)was observed in B100%group as compared with the control.Aspartic acid contents in breast muscle were significantly reduced by substitution of betaine anhydrous for DL-Met(P<0.05).Phenylalanine and proline contents were significantly lower in B25%group than that of the control(P<0.05).B50%and B100%groups decreased the contents of leucine,lysine and total amino acid(P<0.05).B100%group also reduced phenylalanine,threonine and serine contents(P<0.05).Compared with the control,betaine inclusion groups had no effect on glycine content,but glycine content was significantly lower in B100%group as compared with B25%group(P<0.05).B25%and B50%groups increased cysteine contents(P<0.05)as compared with the control and B100%group.The contents of Met,tyrosine,glutamic acid,essential amino acid and non-essential amino acid in breast muscle tended to be lower in betaine inclusion groups(P<0.1).These results implied that Met replacement with betaine anhydrous in diet had no effect on the growth and development and carcass characteristics,but decreased the muscle antioxidant capacity,meat quality and some muscle amino acid contents in a dose-dependent manner.Under the condition of this test,betaine anhydrous replace 25%Met could improve grow performance and not influence meat quality and muscle amino acid contents.